3-Oxopentanedicarboxylic acid esters are compounds useful as intermediates of fine chemicals, such as medicinals and agrochemicals, and as raw materials for polyesters.
Organic Syntheses, Collective Volume 1, page 10 and page 237, for instance, discloses a technique of producing 3-oxopentanedicarboxylic acid which comprises treating citric acid with fuming sulfuric acid to give acetonedicarboxylic acid and esterifying this dicarboxylic acid. In this process, however, the intermediate acetonedicarboxylic acid is unstable and readily undergoes decomposition by heat or by an acid or alkali, for instance. Therefore, when this process is conducted on an industrial scale, the yield of and the selectivity for the desired product 3-oxopentanedicarboxylic acid ester are low.
In Japanese Patent Publication No. 24461/1991 (JP-3-24461B) and Japanese Patent Application Laid-Open No. 78146/1983 (JP-59-78146A), there is reported a method of synthesizing 3-oxopentanedicarboxylic acid from diketene, an alkyl nitrite and carbon monoxide using a palladium catalyst. For obtaining the alkyl nitrite, however, it is in general necessary to react a nitrogen oxide, such as nitrogen monoxide, nitrogen dioxide, dinitrogen trioxide or dinitrogen tetraoxide, which requires care in handling, with an alcohol or water. This reduced the workability and reaction operability.
Therefore, these processes cannot be said to be advantageous from the industrial practicability viewpoint. Further, these processes are essentially incapable of synthesizing unsymmetrical diesters (namely diesters having a structure such that the two ester groups have different alkoxy moieties) and, even if they could be synthesized, they would be obtained only in the form of a mixture of unsymmetrical and symmetrical diesters.
In Swiss Patent No. 659060, a method is disclosed which uses an acetoacetate ester and a chloroformate ester as starting materials. However, this method uses liquid ammonia and sodium amide, which are not always easy to handle on an industrial scale, and, therefore, cannot be said to be an advantageous method from the industrial production viewpoint, either.
On the other hand, Chemistry Letters, 1990, volume 6, pages 901-904 and the Journal of Organic Chemistry, vol. 62, No. 21, page 7114 (1997), for instance, describe a ring-opening reaction of a 6-substituted-4H-1,3-dioxin-4-one under the action of an alcohol or water.
Further, in M. Hidai and M. Ichikawa: "Kagaku Seminar, 11, Kin'itsu Shokubai to Fukin'itsu Shokubai Nyumon--Korekarano Shokubai Kagaku (Seminar in Chemistry, 11, Homogeneous and Heterogeneous Catalysts, An Introduction--Catalytic Chemistry in the Future)", published by Maruzen Co. (1983), page 49, for instance, there is described an ester synthesis by the carbonylation reaction of an aryl halide using a palladium catalyst.
However, there is no description of 6-alkoxycarbonylmethyl-4H-1, 3-dioxin-4-ones and there is no example known of the application of these reaction systems to 6-alkoxycarbonylmethyl-4H-1,3-dioxin-4-ones.